rq_list_peek
struct request *last = rq_list_peek(&plug->mq_list);
struct request_queue *q = rq_list_peek(rqs)->q;
rq = rq_list_peek(&plug->cached_rqs);
rq = rq_list_peek(&plug->cached_rqs);
pdu->req_list = rq_list_peek(l);
static inline struct request *rq_list_peek(struct rq_list *rl)
for (pos = rq_list_peek((rl)), nxt = pos->rq_next; \